The invention relates to material handling apparatus, particularly flowable material such as a powder. It will be understood that the expression particulate material used herein includes powders, grains, granules, dust, tablets, capsules, and the like.
It is often the case that such particulate material--usually held in a container such as an intermediate bulk container (IBC) for transport, storage and general handling--has to be contained in the immediate area of the IBC during discharge through a discharge station to subsequent processing. Such containment is for environmental purposes and/or for the health of operating personnel. Such problems have to a large extent been obviated, for example as shown in U.K. patent specification No. 2084969.
However, required standards for containment are constantly increasing in industries such as those concerned, with pharmaceutical, fine chemicals, or radio-active materials and indeed anywhere where product contamination of atmosphere or personnel is an important factor.
Present day O.E.L. (operator exposure levels) typically are between 1.times.10.sup.-3 and 1.times.10.sup.-5 grammes per cubic meter of air. These levels are no longer sufficient to meet the needs of industry and O.E.L. levels down to 1.times.10.sup.-9 grammes per cubic meter (1 nanogramme per cubic meter) are now required. The only present practical ways to achieve such levels are by use of laboratory scale equipment using glove boxes, full operating protection, breathing apparatus, full environmental air cleaning and conditioning and so on. The problem is that laboratory methods can only process such products in very small quantities whereas industrial process industries require to process and action these toxic materials in large batch quantities in the hundreds and thousands of Kgs. Such prior processes are expensive, time-consuming and impractical for large volumes, particularly as no prior system today is capable of meeting containment O.E.L. levels of 1.times.10.sup.-9 grammes per cubic meter.
The problem is that generally an IBC when removed from a discharge station even with a double lip seal and intermediate cleaning system will still have some amount of product on the bottom exposed edge of a cone valve seal and bin outlet of the system.
There is an item, a transport cap, which is fitted manually or automatically to the outlet to cover these contaminated areas completely and thus to enable the IBC to be moved away with no product exposed, a system incorporating such a cap being now able to achieve higher levels of product containment.
However, between the time that the IBC is lifted up from the discharge station and the transport cap being fitted, product is exposed to the local environment and there is a risk that while the transport cap is being moved horizontally sideways underneath the IBC (between the IBC and the discharge station), and then upwards to engage, some minute particles of product will fall off the edge of the cone valve and bin outlet and contaminate the outer surfaces of the transport cap--(it being accepted that when the transport cap has been moved horizontally into position and lifted upwards the inner surfaces of the transport cap and the exposed surfaces of the cone valve mate and seal together thus protecting these product contaminated surfaces from the outside and vice versa).